India’s PSLV-C61 mission, intended to deploy the advanced EOS-09 Earth observation satellite, failed minutes after launch Sunday morning due to a suspected flex nozzle malfunction in its third-stage propulsion system, according to initial analysis.
The Indian Space Research Organisation (ISRO) launched the Polar Satellite Launch Vehicle at 5:59 a.m. IST from Sriharikota’s Satish Dhawan Space Centre, but the rocket veered off trajectory during the critical third-stage burn.
The 44.5-meter-tall rocket performed nominally through its first two stages, with the solid-fueled PS1 core and PS2 liquid-stage operating as planned. Issues arose 203 seconds into flight during the PS3 solid motor phase, when telemetry indicated a sudden drop in chamber pressure.
Isro Chairman V Narayanan confirmed the anomaly, stating, “First two stages performed as expected. In the third stage, we observed less chamber pressure. The mission could not be accomplished”.
Sources cited a suspected failure in the flex nozzle control system – a critical component that directs thrust by adjusting the rocket nozzle’s orientation.
The third-stage PS3 motor uses a flexible bearing nozzle system to steer the vehicle during its 114-second burn.
Flex nozzles, made of layered elastomeric materials, allow precise thrust vector control without complex hydraulic actuators. A failure here could cause thrust misalignment, leading to rapid trajectory deviation.
ISRO’s PS3 stage employs hydroxyl-terminated polybutadiene (HTPB) fuel, which generates 240 kN of thrust under optimal conditions.
The EOS-09 satellite, designed for all-weather surveillance using C-band Synthetic Aperture Radar, failed to reach its intended 525 km sun-synchronous orbit.
This marks the PSLV’s third failure in 63 launches and its first since 2017. ISRO has convened a failure analysis committee to review manufacturing records and test protocols for the PS3 stage.
The setback delays India’s plans to augment its 52-satellite surveillance constellation.
While the agency has not confirmed the root cause, historical data shows 74% of global launch failures between 2018-2023 involved propulsion or stage-separation issues.
